Field of the Invention
The present invention relates to a radiation imaging apparatus and a control method thereof.
Description of the Related Art
A radiation imaging apparatus can include, for example, a sensor array in which a plurality of sensors are arrayed and a readout unit which reads out a signal from each sensor. Among radiation imaging apparatuses, there is an apparatus that is configured to perform Automatic Exposure Control (AEC) which ends radiation irradiation when a radiation dose to the sensor array reaches a target value.
In Japanese Patent Laid-Open No. 7-201490, some sensors, out of a plurality of sensors, are used as monitoring sensors to monitor the radiation dose, and signals from the monitoring sensors are sampled by predetermined cycles after radiation irradiation is started. According to Japanese Patent Laid-Open No. 7-201490, the above-described AEC is performed based on the result of the sampling performed at predetermined cycles.
In Japanese Patent Laid-Open No. 2010-75556, some sensors, out of a plurality of sensors, are used as monitoring sensors and signals from the monitoring sensors are sampled at least twice after radiation irradiation is started. According to Japanese Patent Laid-Open No. 2010-75556, the above-described AEC is performed by determining the radiation irradiation end timing based on the sampling timings and the results of these samplings.
Since ringing or dulling of the waveform can occur in the pulse waveform of the radiation, problems such as excessive radiation irradiation, mixing of random noise along with an increase in number of samplings or the like may occur. These problems can reduce the accuracy of AEC.